1. Karyotypes and Pedigrees

2. Chromosomes Somatic cells have 23 pairs of chromosomes. Autosomes
chromosome pairs # 1-22
contain genes that are NOT related to gender
Sex chromosomes
Pair # 23
X and Y
Determine gender in mammals

3. Karyotype Map of all 23 pairs of homologous chromosomes.
Used to identify chromosomal abnormalities.
Extra or missing chromosomes
Deletion or duplication of a segment of a chromosome.

4. Nondisjunction
Occurs when chromosomes fail to separate properly during meiosis.
Result is gametes with too many or too few chromosomes.

5. Result of Nondisjunction
Monosomy- missing a chromosome (1).
Karyotype will have 1 chromosome instead of 2.
Trisomy- one extra chromosome (3).
Karyotype will have 3 chromosomes instead of 2.

6. Pedigree Chart used for tracing phenotypes in a family.
Phenotypes are used to infer genotypes. ? ? ? ? ? ?

7. Reading Pedigrees = male = female
If shaded in, individual has the trait.
If half shaded, individual is a carrier (has the gene but not the trait).
Carrier has the gene but does not have the physical trait. Cannot be a carrier of a dominant trait!
A white shape (not shaded) indicates the individual does not have the gene.

8. Practice reading the pedigree below? ? ? ? ? ?

9. Pedigrees and Chromosomes
If trait occurs equally in males and females, it is probably on an autosome.
If trait is far more common in males, it is probably on a sex chromosome.